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Solution

The above error occurs when the direction of a port is not specified for any of the arguments in the function definition. In the above example code, the port direction of argument [0:3] a,b for function oring is not specified, which causes the compiler to error out with HDLCompiler:1830.

Please note that you can change this error message to a warning by using the XST switch: -change_error_to_warning "HDLCompiler:1830", as mentioned in the INFO message.